KR101222273B1 - Continuous and semi-continuous treatment of textile materials integrating corona discharge - Google Patents

Abstract

Corona in continuous and semi-continuous methods for processing cotton, flax, cotton / flax blends or other cellulosic materials in any form, such as yarn, fiber fabrics or knitted fabrics, to increase complete hydrophilicity and network potential It relates to using a discharge.

Processes that include corona discharge include firing, alkali treatment, bleaching, causticization, mercerization, dyeing and final processing, i.e. softening, hydrophilization, trim-easy, preshrunk and fire resistant. The discharge is applied continuously in an open width material having controlled humidity and temperature in the raw, baling, bleaching or processing steps, the material being designed to generate a high voltage discharge in a completely uniform state, the electrode The rolled phase of the counter electrode, which is arranged at a close distance to, is moved at a controlled speed.

Corona discharge, continuous and semi-continuous processing, hydrophilization, reticular potential

Description

CONTINUOUS AND SEMI-CONTINUOUS TREATMENT OF TEXTILE MATERIALS INTEGRATING CORONA DISCHARGE}

The impregnation process requires extremely harsh conditions when material uniformity is a problem. At this level, even the slightest imperfections cause irreparable damage to the quality of the product.

All cellulosic fibers are hydrophobic, especially in the untreated stage, because large amounts of impurities form a barrier to the aqueous solution, preventing penetration and diffusion in the fiber structure. Impregnation of this type of fabric provides a high and completely uniform ability with respect to the adsorption of solutions in order to obtain optimum yields and homogeneous results in preparation, dyeing, printing and final processing during continuous and semi-continuous processing. Require. Since it is naturally hydrophobic, it is extremely difficult to satisfy these harsh conditions. Indeed, in order to eliminate this technical problem, it is necessary to use several wetting agents to reduce the speed of the material or to raise the temperature of the impregnation solution. The most important consequences of this practical method are:

The use of humectants in the method of impregnation solution means that there are problems associated with increased costs, increased pollutant emissions and foaming.

• A decrease in speed means a decrease in production volume.

Increasing the bath temperature means an increase in the cost of energy and is likely to cause the formation of aggregates of products present in the impregnation bath.

The advantage of pre-uniformly hydrophilizing the cellulosic material to be impregnated with the pullar fabric is considered to be of fundamental importance, and it is fundamentally supported by the introduction of corona plasma technology, which has been modified and impregnated in a controlled state. It is thought that extremely desirable behavior can be realized.

In corona treatment, discharge occurs between the electrode and the counter electrode grounded to the ground while maintaining a potential difference of about 10000 volts. The fabric moves continuously between the electrodes at a controllable speed and sufficient tension.

The temperature and humidity of the material are determined to optimize the discharge effect. The temperature of cotton should be set at 40 ℃ or lower and the humidity should be 8% or lower. The discharge is done in air at ambient pressure and temperature.

The main cellulosic fibers subjected to corona discharge are blends with synthetic and artificial fibers if cotton, flax, hemp and cellulose are present in higher proportions. An extremely large number of cellulosic fibers, which are rarely used in the textile industry, can also be treated using this technique.

The present invention relates to the use of corona discharges in continuous and semi-continuous lines to treat cellulosic materials to increase hydrophilization and network potential.

Processes that are directly affected by physical and chemical changes induced by plasma discharge in the structure of the fabric material are desizing, alkali treatment, bleaching, causticization, dyeing, printing and processing.

Corona discharges occur in air under normal atmospheric conditions while continuously moving the fabric material.

Corona discharge is generated between the two electrodes at high pressure and at a frequency of 20-40 kHz at atmospheric pressure and temperature.

This technique is widely applied in the plastics field to increase the adhesion between impression links and the substrate and is fully established in this field. In the plastic polymer film, the processing speed of the material is high speed, such as up to 450 m / min, and the width can be widened up to 10 m for extremely uniform treatment. For example, US Pat. No. 5882423, "Plasma cleaning method for improved ink brand permanency on IC package," uses plasma to realize the removal of contaminants in metal, ceramic, and plastic components of integrated circuits, resulting in higher surface energy, which is a material. A method is described that allows for better adhesion than ink to.

If the discharge is at a voltage of 400-800 V and low pressure (1-100 mbar) in the frequency range of 1 MHz-2.1 GHz, this treatment is referred to as "plasma" or "glow discharge" in the special case of the plasma medium. This particular treatment is already known in the textile industry and offers the possibility of doing well at several gaseous media and pressure levels to achieve significant effects. This method of treatment is used to improve the shrinkage, hydrophilicity and spinning ability of wool fibers, but in the case of very expensive and classical forms [1], [2] and [3] it is required to treat at vacuum pressure.

Corona discharge technology is also used in the process for improving the dyeing and obtaining the properties of anti felt for wool fibers. European patent EP0548013 "Process for dyeing of wool with help of low-temperature plasma or Corona pre-treatment" is intended to perform surface corona pre-treatment, and then to dye in an aqueous bath, avoiding the final treatment with chloride without leveling agent. The process to include is described. Regarding the anti-felt properties, US Pat. No. 6,030,68 "Process for anti-felting finishing of wool using a low-temperature plasma treatment" includes a process of performing anti-felt finish on wool by high-temperature, low-temperature plasma discharge treatment. It is described.

Corona treatment is also used to increase the adhesion of the coated fabric. European Patent GB 2279272 "Process for coating textile fabrics with elastomers" describes increasing the adhesion of the silicone layer to the fabric fibers in the coated material by performing a corona discharge.

1 is a view showing the absorption time of water droplets by a cotton fabric according to the number of corona discharges for different power levels.

2 is a view showing the power resistance of the slope of the cotton fabric according to the number of corona discharge.

3 is a view showing the absorption time of the water droplets by the linen fabric according to the number of corona discharge.

4 shows a corona discharge applicator for a fabric material.

The new non-contaminant technology is basically based on physical means for generating plasma in either low pressure or atmospheric conditions, as in the case of corona. These technologies are the best solution for designing cleaner and more economical methods and at the same time obtaining high quality products, and are considered unique opportunities for ecologically convenient optimal methods at reasonable costs.

Since the conventional textile industry still feels uncompetitive, a fast and innovative solution is needed to help solve this problem. For this reason, the application of corona technology in this area has been considered in consideration of being the simplest option since it has the proven advantages in terms of efficiency of the method, allowing the possibility of continuous and semi-continuous operation.

The application of corona technology in textile materials, ie cellulosic fibers, poses particular problems with high energy requirements, but for continuous and semi-continuous processes operating at high speeds such as 60 m / min for a maximum fiber width of 3.60 m. I think it's a very convenient solution.

The development of new solutions for the application of corona technology in the processing of textile materials has been achieved by the University of Minho and collaborators in order to take full advantage of improvements in hydrophilicity, uniformity and surface reactivity.

The fabrication of a laboratory prototype of corona discharge, which combines a system consisting of ceramic electrodes with counter electrodes of a certain role, and is carried out by continuously moving the fabric, is a practical study of new methods that studies the scientific basis for accurate system analysis. There is the possibility of evaluating the advantages, economic and ecologically beneficial effects. Discharges occur between electrodes that maintain a voltage difference of about 10000 V. The temperature and humidity of the material are determined to optimize the discharge effect and to prevent damage to the fabric. That is, for cotton fiber fabrics the temperature is below 40 ° C. and the humidity is below 8%.

An increase in the surface roughness of the cotton fibers after the corona treatment is detected because of the "cleaning effect" in which the passages are formed which contribute to the beneficial influence on the access of the solution and the product in the fiber.

In chemical terms, corona treatment produces surface oxidation that affects the behavior of materials in industrial processing. The untreated cotton had an average atomic composition of 82.9% carbon and 14.7% oxygen, and low levels of magnesium, potassium and sodium were detected. After corona treatment, a decrease in carbon concentration of up to 57.8% was detected, and a significant increase in oxygen up to 37.3% was detected. These values are very close to the values provided by pure cellulose. The group of C-O, OCO and COO has increased significantly, making access to cellulose located beneath the waxy surface faster and more efficient.

The model relating to the behavior of cotton fibers is created by showing the relationship between the hydrophilicity obtained after the treatment and the discharge conditions such as the discharge force, the number of discharges, and the speed of the textile fabric. One example is shown in FIG. 1. Using these variables, the corona dose was calculated for a given treatment width and compared with other embodiments.

As the number of corona passes increased, the mechanical resistance of the raw cotton fiber fabric was tested and a larger value was obtained (FIG. 2).

In the case of hydrophobic linen fiber fabrics, the change in hydrophilicity according to the number of corona discharges is shown in FIG. 3, and similar changes were observed when compared to the behavior of cotton.

Particularly when the process is continuous and semi-continuous [4], [5], [6], [7], the discharge is characterized by physical and chemical effects on the surface by hydrophilization and increased reactivity, namely firing, alkali It has been demonstrated that it can cause effects in treatment, mercerization, dyeing, processing and printing processes.

Unexpected results were obtained when merging untreated or braided cotton fiber fabrics without the use of any type of wetting agent, compared to non-corona fiber fabrics with high levels of efficiency and uniformity. The amount of barium was increased by up to 60%, resulting in a blend of flax / cotton blends as well as 100% linen products.

With regard to the behavior of the fabric during the impregnation by padding using dyeing and processing baths in continuous and semi-continuous processes, it is possible to obtain higher pickup rates and uniformity without the use of wetting agents. This, in turn, means better end results in more economical and ecological ways.

In general, uniform corona discharges on cotton and flax materials can be obtained using energy levels that are fully adapted to industrial practice at several stages of the process.

The principle of the corona treatment device for the woven web is shown in FIG. 4. As a main component, it is comprised from the electrode which has the some electrode bar 1, and the counter electrode 2. Here, the counter electrode 2 is preferably a moving counter electrode supporting the moving fabric web 3. A sufficient sine wave shape or pulsed phase voltage of 5000 to 30000 volts, preferably 10000 to 15000 volts, and a frequency of 10 to 100 kHz, preferably about 30 kHz, is applied to the electrode bar 1 to counter the electrode bar 1 and the counter electrode. Corona discharge 4 is generated and maintained between (2). The counter electrode 2 is grounded, and this process usually proceeds under atmospheric pressure. Corona discharge 4 improves the hydrophilicity and network potential of the fabric material.

The electrode consists of a plurality of electrode bars of dielectric (not shown in FIG. 4), preferably ceramic, which are arranged at a distance of preferably 1.5 mm relative to the counter electrode 2. A gaseous medium 5, preferably air, is injected between the electrode bars 1 to cool the electrodes. The gas distribution chamber 6 with slots maintains the same gas flow along the width of the electrode bar 1.

The electrode composed of the electrode bar 1 and the gas distribution chamber 6 and the counter electrode 2 are surrounded by a housing 7. The housing 7 has an inlet 8 and an outlet 9 of the textile web 3. Exhaust gas 9 containing ozone and other gaseous components is absorbed through hose 10 by a fan, although not shown in FIG. 4.

The distance between the electrode bar 1 and the counter electrode 2 is at least 0.8 mm, preferably 1.5 mm and 3 mm or less. This interval is set by moving either the electrode comprised by the electrode bar 1 and the gas distribution chamber 6, or the counter electrode 2. As shown in FIG.

The counter electrode 2 is a rotating drum coated with a dielectric (not shown in FIG. 4), preferably silicon or ceramic, and carries the fabric web 3. Movement of the fabric web 3 proceeds at a controlled speed. For temperature control, the counter electrode 2 is in the form of a double skin drum and can be heated or cooled by gaseous or preferably liquid medium.

Depending on the speed of the fabric web 3, a plurality of devices consisting of electrodes and counter electrodes can be used to process the fabric web 3. These devices can process either one or both sides of the woven web 3.

The wet process of cellulosic fiber fabrics comprises a plurality of steps:

Preparation steps whose main purpose is cleaning, hydrophilization, stabilization and bleaching of the dimensions;

A dyeing step of applying and fixing the dye;

A printing step of applying and fixing a printing paste or ink; And

ㆍ final finishing stage to improve a wide range of characteristics by applying specific products and treatments.

It is proposed to integrate corona treatment in the wet treatment line of cellulosic material, suggesting the following options:

Corona discharge is applied before enzymatic call.

This process would be beneficial as the fabric would be hydrophilic even in the absence of humectant in the impregnation bath used for padding in continuous and semi-continuous processes. Deeper motion over the incline ensures more uniform results with respect to the removal of the protector. Inactivation of enzymes by tension activation is also avoided.

If the arcing is carried out by dissolution in water, the swelling of the protector is accelerated and accelerated.

Corona discharge can replace refining.

In a process line that includes an independent refining treatment, this operation aims at hydrophilization by removing wax and oil phase material. If the corona discharge is carried out in a gray material, the penetration of the solution can be realized with a minimum amount of chemicals. Furthermore, it is possible to remove natural impurities in the oxidation / alkaline bleaching treatment.

Corona discharge can be carried out by pre-treatment of causticization or mercerization processing.

These processes employ a high concentration of alkaline solution and are continuously applied to untreated, called or semi-bleached materials during a short contact time. If the corona discharge is performed in advance, the problem of insufficient penetration of the solution into the fabric and the fiber can be solved. This is particularly important if the material is still hydrophobic in the non-swelled state and would be significantly beneficial in increasing mercerization action. The use of a humectant is possible to improve the contact of the solution and the penetration of the solution into the fabric, while at the same time the important problem of chemical resistance to alkali and the appropriate choice for recovery of the effluent is solved through corona discharge. There is a number.

Pre-hydrophilizing the fabric using corona discharge will contribute to significantly increasing the proportion of mercerized fibers, which means higher cost quality while reducing costs and reducing environmental problems.

Corona discharge can be applied to flax, hemp and blends.

In the special case of making linen fabrics and hemp materials, penetration of solutions is quite difficult because of the crystalline structure or the high levels of natural impurities present when compared to cotton fabrics. Corona discharge on linen materials can realize hydrophilization without the use of chemicals.

Corona discharge ensures uniformity and higher pick-up rate in the padding process.

By discharging before padding in the pad-batch, pad-roll or pad-steam process used to dye cellulosic fabrics in a complete and uniform manner without the use of humectants, even when the material is insufficiently prepared Can be impregnated In some cases, it is thought that it is enough to dye black. When dye penetrates highly into a fiber, it means that the irreversibility of a dyeing process increases.

Corona discharge increases fixation of resin and binder in final processing and printing processes.

Increasing the reactivity potential of the surface of the fabric material is achieved by chemical modifications induced by corona discharge, and the advantages of this technique are softening, shrink-proofing, easy-to-use, refractory treatment, and fixing of printing pastes with pigments by binders. To the field of In addition, the application of the processing solution to the material treated by the corona ensures to increase the uniformity and hydrophilicity of the processed product.

References

Claims (22)

a. Moving the cellulosic material between the electrode and the counter electrode; b. Applying a sinusoidal shape or an impulse electric discharge while maintaining a potential difference between 5000 and 30000 volts between the electrode and the counter electrode, wherein the electrode and the counter electrode are configured as dielectric barriers; And c. A method of non-pollution treatment of cellulose-based material, comprising cooling the electrode and counter electrode using a corona discharge at atmospheric pressure and temperature that can increase oxidation, hydrophilization, and network potential of cellulose-based material. The method of claim 1 wherein the cellulosic material is a fabric. The method of claim 1 wherein the potential difference is between 10000 and 15000 volts. The method of claim 1, wherein said moving step is continuous or semi-continuously at a controllable speed. The method of claim 1, wherein the sinusoidal shape or impulse electric discharge is applied with a frequency in the range between 10 and 100 kHz. 6. The method of claim 5, wherein the sinusoidal shape or impulse electric discharge is applied with a frequency of 30 kHz. The method of claim 1, wherein the method wets the binder completely and uniformly during impregnation while simultaneously adhering the resin and the binder. The method of claim 1 wherein the non-pollution treatment of the cellulosic material is arcing, refining, bleaching, causticization, mercerization, dyeing, printing and processing. 2. The method of claim 1, wherein in applying the sinusoidal shape or impulse electric discharge, the sinusoidal shape or impulse electric discharge is performed on a wide fabric at a controlled temperature, humidity, and speed in a callout, bleaching, and processing condition. How to. The method of claim 2 wherein the fabric is selected from the group consisting of blends with synthetic or artificial fibers if cotton, flax, hemp and cellulose are present in higher proportions. a. It consists of an electrode having a plurality of bars (1) and a rotating counter electrode (2), the electrode and the counter electrode is composed of a dielectric barrier, b. A gas distribution chamber 6 disposed between the bars 1 made of electrodes and for cooling the electrodes; c. Apparatus for processing textile material, comprising a gas outlet (10). The processing apparatus according to claim 11, wherein the gas distribution chamber has an opening that is evenly distributed along the width of the bar. 12. The processing apparatus according to claim 11, wherein the electrode is made of a ceramic material, and a distance from the counter electrode (2) is spaced between 0.8 mm and 3 mm. The processing apparatus according to claim 13, wherein the electrode is spaced 1.5 mm apart from the counter electrode. The processing apparatus according to claim 13, wherein the interval is adjusted by moving either an electrode composed of the bar and the gas distribution chamber or an opposite electrode. 12. The processing apparatus of claim 11, wherein the counter electrode is a rotating drum coated with a dielectric barrier for transporting textile material. 17. The processing apparatus of claim 16, wherein the dielectric barrier is made of silicon or ceramic material. 17. The processing apparatus of claim 16, wherein the rotating drum has a double skin drum capable of controlling temperature. 19. The processing apparatus of claim 18, wherein said temperature control is performed using a gas or a liquid medium. The processing apparatus of claim 11, wherein the number and shape of the electrodes depend on the speed of the fabric material. 21. The processing apparatus of claim 20, wherein one side of the fabric material is treated. 21. The processing apparatus of claim 20, wherein both sides of the fabric material are treated.

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